804 ÷ 3 = 268 R0
We're going to perform division on 804 with 3 as the divisor.

Step 1:
3 goes into 8 2 times with a remainder of 2.
Write down 2 as next digit of of the result. 
Result so far: 2
Subtract 6 from 8 to get 2.
Bring next digit (0) of the dividend behind the 2 and repeat the process: 20 / 3

Step 2:
3 goes into 20 6 times with a remainder of 2.
Write down 6 as next digit of of the result. 
Result so far: 26
Subtract 18 from 20 to get 2.
Bring next digit (4) of the dividend behind the 2 and repeat the process: 24 / 3

Step 3:
3 goes into 24 8 times with a remainder of 0.
Write down 8 as next digit of of the result. 
Result so far: 268
Subtract 24 from 24 to get 0.

The final result is 268 with a remainder of 0.